The passenger car and the freight car leave from a and B at the same time. The passenger car runs 50km per hour, and the speed of the freight car is 80% of that of the passenger car. After meeting, the passenger car continues to travel for 3.2 hours to reach B. how many kilometers are there between a and B?

The passenger car and the freight car leave from a and B at the same time. The passenger car runs 50km per hour, and the speed of the freight car is 80% of that of the passenger car. After meeting, the passenger car continues to travel for 3.2 hours to reach B. how many kilometers are there between a and B?

(50 × 3.2) △ (50 × 80%) = 160 △ 40 = 4 (hours) (50 + 50 × 80%) × 4 = (50 + 40) × 4 = 90 × 4 = 360 (kilometers) answer: A and B are 360 kilometers apart

The proposition "there is a real number x such that x ^ 2 + 1"

The negation of proposition is what you write,
The converse proposition is the opposite of the conclusion and condition, that is, if x ^ 2 + 1 & lt; 0, then there is a real number X
Proposition negation is the condition of negation and the conclusion remains unchanged

A and B trains are running at 54 km / h and 36 km / h respectively
On a straight track, trains a and B are heading towards each other at the speed of 54 km / h and 36 km / h respectively. A bird flies away from the front of train a at the speed of 20 m / s, flies back to the front of train B immediately, flies back to the front of train a, turns back to the front of train B immediately, and flies back to train B again and again until the two trains meet. It is known that the total flight distance of the bird is 400 m, At the beginning, when the bird flies out from the front of car a, the distance between the two car heads is very small
A. 500 m B. 600 m C. 300 M D. unable to judge

Here's how to do it: the bird flew 400m, which means it flew 20s. The speed of a is 15m / s, and that of B is 10m / s,
So the distance is (15 + 10) * 20 = 500m, choose a

The average number of the three numbers is 6, and their ratio is 1 / 2:2 / 3:5 / 6. The largest of the three numbers ()
The average of the three numbers is 6, and their ratio is 1 / 2:2 / 3:5 / 6, which is the largest of the three numbers（
The ratio of the two right sides of a right triangle is 3:4. The sum of the length of the two right sides is 14 cm, the length of the hypotenuse is 10 cm, and the height of the hypotenuse is () cm?

Hello! The average number of the three numbers is 69. The ratio of the three numbers is 1 \ \ / 2 to 2 \ \ / 3 to 3 \ \ / 4. The largest number among the three numbers is (54) and the smallest number is (81)

The speed of car a is 7 / 9 of that of car B. the two cars are going towards each other from both places at the same time. They meet 8 meters away from the midpoint to find the distance between the two places

The speed of car a is 7 / 9 of that of car B. the two cars are going towards each other from both places at the same time. They meet 8 meters away from the midpoint to find the distance between the two places
Distance ratio = 7:9
Distance between meeting point and midpoint: whole distance = 9 - (9 + 7) / 2: (9 + 7) = 1:16
Distance between the two places = 16 x 8 = 128 m

We know that: 9 = 3 × 3, 16 = 4 × 4, here 9 and 16 are called "perfect square numbers". In the first 300 natural numbers, remove all "perfect square numbers", what is the sum of the remaining natural numbers?

17 × 17 = 289, 18 × 18 = 324, so the largest of the complete square numbers within 300 is the square of 17; these complete square numbers are: 1 × 1 = 1, 2 × 2 = 4, 3 × 3 = 9, 4 × 4 = 16, 5 × 5 = 25, 6 × 6 = 36, 7 × 7 = 49, 8 × 8 = 64, 9 × 9 = 81, 10 × 10 = 100, 11 × 11 = 121, 12 × 12 = 144, 1

On the map of China with a scale of 1:6000000, it is measured that the distance between the two places is 10 cm. The two trains leave from the two places at the same time and meet six hours later. It is known that the speed ratio of the two trains is 11:9. How many kilometers do they travel when they meet?

First calculate the actual distance 10 * 6000000 = 6000000cm = 600km
According to the speed ratio, it can be calculated that car a has run 330km
❤ your question has been answered ~ (> ^ ω)^

If x, Y > 0. X + y = 1

Two sides square, x + y + 2 roots, xy = 2 roots, XY;
So square a = 2
So a > = root 2

A motorcade transports a pile of coal. On the first day, it transports 1 / 6 of the pile of coal. On the second day, it transports 40 tons more than on the first day
A fleet transports a pile of coal. On the first day, it transports 1 / 6 of the pile of coal. On the second day, it transports 40 tons more than on the first day. At this time, the ratio of the transported coal to the remaining tons is 7:5. How many tons of coal is there?

At this time, the ratio of the transported coal to the remaining tons of coal is 7:5, that is, the transported coal accounts for 7 / (7 + 5) = 7 / 12 of the total
Total: 40 / (7 / 12-1 / 6-1 / 6) = 160 tons

1. If a and B are positive real numbers and 1 / A + 1 / b = 1, then the maximum value of (2 + b) / 2Ab is?
2. It is known that a, B, C and D are all positive numbers, s = A / (a + B + C) + B / A + B + D + C / A + C + D + D / C + D + B
A.0